Pressure operated circuit breaker



Nov. 18, 1947. o. voN MEHRx-:N Erm.

PRESSURE OPERATED I CIRCUIT BRAKER Filed Feb. 16, 1945 5 Sheets-Sheet 1 lATTORN Y Nov. 18, 1947. A o. voN M'EHREN ETAL 2,431,286

PRESSURE OPERATED CIRCUIT BREAKER Filed Feb. 16, 1945 .3 sheets-sneetz ATTORNE Nov. 18k, 1947. o, VON MEHREN TAL 2,431,286

PRESSURE OPERATED clEcUIT 'BREAKER Filed Feb. 16, 1945 5 Sheets-Sheet 5 Patented Nov. 18, 1947 UNITED STATES PATENT OFFICE PRESSURE OPERATED CIRCUIT BREAKER Oswald von Mehren, Wilkinsburg, and Benjamin P. Baker, Turtle Creek, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 16, 1945, Serial No. 578,196

Multipole fluid blast circuit breaker equipments have been designed for operation by iluid under pressure and have been successfully employed for classes of service for which well known types of magnetically actuated' oil circuit breakers were once considered essential. Difculty has heretofore been encountered, however, in devising fluid pressure operating mechanism for a porcelain-clad circuit breaker, which can be em- 23 Claims. (Cl. Zim- 82) association with porcelain structural elements of the circuit breaker and which may be safely operated by uid under high pressure Without risk of damage to the porcelain members.

A further object of our invention is the pro- Vision of a fluid pressure responsive operating mechanism of the above type in which is included automatic locking means operative to check any x undesired shifting of the movable contact out of ployed where space is at a premium and in which the usual piston can be safely operated under high fluid pressure Without transmittal of excessive shock or vibration to the circuit breaker structure. It iscustomary to provide structural elements of an insulating material, such as porcelain, for supporting sections of this type of circuit breaker. The provision of an efficient form of shock absorber mechanism in association with the iluid pressure operating device is thus particularly desirable to avoid the possibility of damage to these relatively fragile structural supporting members. In order to insure maintenance of the movable Contact elements of a fluid pressure actuated circuit breaker in circuit closed position, it has further been found advisable to provide a form of mechanical locking means cooperative with the movable Contact elements. While locking mechanisms already proposed have had a measure of success under service conditions, difculty may be experienced in effecting suiiiciently rapid release thereof during an opening operation of the circuit breaker. In addition, certain types of these devices have in the past been of rather complicated and bulky construction.

It is an object of our invention to provide an improved fluid pressure responsive operating mechanism for a circuit breaker embodying means for absorbing shock during operation of the usual piston and having parts constructed and arranged to occupy a relatively small space.

Another object of our invention is the provision of an improved fluid pressure responsive operating mechanism for a circuit breaker adapted to insure quick acceleration of a movable contact member from a position of rest in oper ating the circuit breaker.

Still another object of our invention is to provide a compact cylinder and shock absorbing assembly for a `fluid pressure operated circuit breaker, which is adaptedfto be installed in close its circuit closed condition when fluid under pressure is not supplied to the mechanism, together With means for quickly releasing the locking means and accelerating actuation of the mechanism when fluid is supplied to effect a normal operation of the circuit breaker.

`It is a further object of our invention to provide an improved lluid pressure operating mechanism for a circuit breaker having features of the construction already mentioned, in which the relatively feW sturdy operating parts are so devised and proportioned as to facilitate assembly and adjustment, both during the manufacture of the equipment and when the circuit breaker is being serviced.

Other objects and advantages of the invention will appear in the following more detailed de# scription thereof, taken in connection with the accompanying drawings, in which:

Figure 1 is a fragmentary View, partly in sec tion, of a pole unit of a multipole circuit breaker equipment embodying a fluid pressure responsive operating mechan-ism constructed in accordance with the invention;

Fig, 2 is an enlarged-detail view of the operating mechanism of the equipment shown in Fig. 1, with the cover removed; and

Fig. 3 is an enlarged-detail sectional View of a. portion of the operating mechanism shown in Fig. 2.

The fluid pressure operated circuit breaker equipment with which our invention is preferably associated may have a construction generally similar to that illustrated in United States Patent No. 2,342,809, issued to L. R, Ludwig et al. on February 29, 1944, and assigned to the assignee of the pres-ent invention. As shown in Fig. l, such a circuit breaker equipment comprises a base structure including hollow porcelain supporting columns IU and l l ,'a fluid pressure reservoir and suitable control valves and operating `mechanisms therefor (not shown), and three pole units each having a housing 3 and an arc `eX- tinguishing structure 4 supported in insulated relation on the base structure. In each of the D016 13.1.1125 iS, provided a stationary Contact element 5, a movable contact member 22 engageable therewith, and a fluid pressure responsive operating mechanism contained within the housing 3 for actuating the movable contact member in accordance with the supply or release of fluid under pressure, as eiected by operation of the valves carried in the base structure.

In Fig. 2 of the drawings, the .operating -portion of one of the pole units of a circuit breaker equipment of the type shown in the aforementioned patent is illustrated without the outer housing, including the supporting columns or members I8 and II, and a casing section I2 having a lower base portion I3 bolted to the porcelain supporting members and an upper flange portion I5 which is also connected by means of bolts to a transversely disposed structural element 1.6. Carried on the upper flange I5 of the casing section is a member I8, which is provided with spaced linger portions I9 and may constitute a terminal conductor of the circuit breaker. Disposed .above member I8 is a hollow porcelain blast .conduit 20, the lower end of which may .be resiliently supported ina carrier .element 2I mounted .upon a flange of the member I8. As is best shown in Fig. 1, the .porcelain blast conduit 2!) is .substantially vertically disposed and is adapted to sup.- port the karc .extinguishing structure 4 yand an upper insulating column 6 having mounted therein the stationary contact member .5. The latter is adapted to be slidably engaged .by .the movable contact member 22, the lower .end '.of which is slidably vengaged by portions I9 of member I8. The `contact member 22 is operatively connected to a piston forming part of a fluid pressure responsive operating mechanism, generally indicated vby the reference character 25, which is disposed within the housing ,3. I t will be noted :that the contact member 22 is movable a short distance into the contact member 5 and thus traverses a closed circuit zone before opening -the circuit. The operating mechanism 25 further comprises ya vertica-lly disposed .cylinder 26 (see Fig. 2) which is adapted to .contain .the piston for operating the contact member 2-2, :as hereinafter explained, and to which fluid `under pressure may -be supplied and released by A,operation of a valve -mechanism 28 mounted on the casing section I2. In the for-m of the equipment illustrated in Eig. 2 the lower end .of cylinder 26 is provided with a suitable shock Yabsorbing assembly 29.

The valve mechanism 28 is not shown in detail, but it will be understood that this mechanism may be similar in construction to that shown in the aforementioned patent, .and is operative when uid under pressure is supplied thereto by way lof a pipe 30 to establish communication between that pipe and a pipe 3| leading to the lower portion of the `cylinder 26 while venting the ,upper portion of the `cylinder to the atmosphere by-way of a pipe 33 .and a suitable ,exhaust por-t (not shown). The piston and `contact member 1272 are thereby moved .to a circuit closed position, The valve device 28 is, on the other hand, operative when fluid under pressure is supplied `to a pipe 36 to connect that pipe to the pipe 13.3 -leading-,to the upper .portion of the cylinder 2-6, While at the same .time isolating .the pipe Y3l) vand com necting the lower `pipe .3| to .an atmospheric exhaustport, `in order to effect operation of fthe movable contact member to its open circuit position.

The casing section I2 .is provided with a conduit portion 38, the lower .end of which QQmmulQteS with a passage (not shown) formed within the porcelain supporting member I0, and the upper end of which communicates by way of suitable apertures in member I8 with the passage 39 eX- tending through the hollow porcelain blast conduit 2D, thus providing an uninterrupted passageway th-rough which a blast .of Vfluid .under pressure may be directed upwardly for extinguishing the arc drawn when the movable contact element 2 2 is moved away from the usual stationary contact element of the circuit breaker. Suitable valve means, -not shown in the drawings, may be provided Ifor controlling the flow of fluid under pressure to the porcelain conduit or supporting member Il! .at ,one time, and to the pipe 30 of the .control valve device 28 at another time. The .pipe 36 is connected to the conduit portion 38 of the casing section.

The construction and arrangement of the valve device 28 and other operating valves for the circuit `breaker is well understood .by those skilled inthe art, so that -a .detailed recital of the -function .of .the elements ,thus far described is not necessary. In brief, when it is `desir-,ed .to effect an opening operation of the circuit breaker, fluid under pressure ris supplied by suitable control valve means `(not shown) to the porcelain conduit member I0 .and iows :through the conduit .38 ,to the passage 39 within the `blast .conduit 20 and also through pipe 36 to the control valve device .28, which .is thereby .operated vto supply a portion of the fluid Cunder pressure through pipe 3 3 .to the .upper portion Aof the vcylinder V2li. At thesame time, it will be understood .that ,the control valve device .28 vents the tlower end `of the ,cylinder .26. In order to `eiect a. closing operation of the .circuit breaker, the supply of lfluid under pressure'. to the porcelain conduit VI0 is :out off by meansof lthe valve devices, -not shown inthe draw-ings, and uid -under pressure is supplied through pipe 30 -to the oQntrol device 28 -whic-his thereby operated to supply fluid under pressure .through pipe 3| to the flower end of the .Cl-vlinder .26. The control valve device 28 then also establishes communication from -the pipe 33 to the atmosphere.

Referring to Fig. 3 of the drawings, fthe 4fluid pressure responsive operating mechanism 2,5 comprises, in addition to the cylinder 2.6, an annular casing section 4f| which has an interior annular shoulder .42 supported on a complementary shoulder 43 of the cylinder, and a substantially .cylindrical body 44, the lower end of which is adapted to be supported on an exterior annular shoulder 46 for-med on the casing section .41. Suitable means (not shown) maybe provided for fir-miv securing the cylinder 2 6, casing section 4I and body 44 together. It will be noted that the body 44 is of Ylarger diameter than that of the cylinder 26 and has an inner wall 45 spacedfrom the `outer wall `of the cylinder. The .upper end 41 Qf the body .44 issomewhat reduced in diameter .and has formed therein .a lbore 48 which is, like .the wail 45., .coaxially .aligned with the cylinder 26. Also formedon the body 44 is a valve portion .50 having a valve chamber .5I which is `open to the atmosphere, .and a valve chamber 52 which communi- Cates kwith the valve chamber 5.I, with pipe 3l. and l.also with a port 53 formed in .the body. The valve chamber 52 has mounted therein a ball check valve 55 for preventing .back flew of fluid therefrom to the pipe 331, Awhich leads to the lower end of the cylinder 2.6 and to the control valve vdevice -28 as l,already,explained inconnection with Fig. 2. M ountedin yalve chamber 5I is a ball check valve 51 which is `normally held in seated position Aunder the force exerted by a spring 58 to limit the pressure of fluid obtainable in the valve chamber 52, for a purpose hereinafter explained.

Secured to the movable contact member 22 of the circuit breaker is a piston 60, which is slidably mounted in the cylinder 26, and has at its lower side a pressure chamber 6l and at its upper side a pressure chamber 62. When the circuit breaker is to be oper-ated to circuit closed position, fluid under pressure is supplied to the lowermost end of the cylinder 26 and acts in the pressure chamber 6| to force the piston 60 and movable contact element 22 upwardly. In operating the circuit breaker to circuit open position, fluid under pressure is supplied to the piston chamber 62 for forcing the piston 60 downwardly, as hereinafter more fully explained.

The piston 60 carries locking means for limiting downward movement thereof in the event that an external force, other than that of the fluid pressure, tends to cause the contact member 22 and the connected piston to move away from the circuit closed position in which these elements are shown in Fig. 2. This locking means comprises a pair of spaced locking elements 64, which are in the form of disc segments slidably mounted for lateral movement in suitable grooves formed in the upper portion of the piston 60, which upper portion is adapted to be disposed above the cylinder 26 when the contact member 22 is movedfto the upper limit of its circuit closed position. Two

coil springs 65, one of which is shown in the drawings, are interposed between the outer ends of the oppositely disposed locking elements 64 for urging them outwardly toward a position permitting these elements to engage the upper end 66 of the cylinder 26. It should be understood that the Contact member 22 will still engage the stationary contact 5 (see Fig, l) while moving from the uppermost position as indicated in Fig. 3 to the position in which elements 64 can engage the cylinder 26. T0 permit continued downward movement of the piston beyond this closed circuit zone, for opening the breaker, the grooves within which the locking elements 64 are mounted are of such depth as to permit the elements to be forced inwardly for entering the cylinder 26 in a manner ing the outer surface of the cylinder 26, to permit movement of the abutment in telescoping relation with the stationary elements, The upper end of the movable abutment 68 extends into the passageway 39 in insulator 28 and has an opening 16 through which slides the movable contact member 22. It will-be lapparent that by thus constructing the blast conduit 20 to receive the upper portions of the body 41, movable abutment 68 and other associated elements of the operating mechanism 25, the over-all dimensions of the circuit breaker, can be effectively minimized without altering the desired insulating characteristics of the equipment. As is best shown in Fig 1 of the drawings, the length of the cylinder oroperating mechanism 25 exceeds the distance between insulators lil-II and blast conduit 20. Fitted about the Contact member 22 within the abutment 68 are a plurality of dished annularspring washers 12, which are nested in groups for providing a resilient cushion between the` abutment and the upper end of the piston 60. The annular spring washers 12 may be held in place by means of a plurality of screws 13 inserted in suitable openings formed in the movable abutment 68.

A plurality of vertically disposed cam portions or ribs 15 are formed on the inner surface of the movable abutment 68 for engagement with the locking elements 64, as shown in Fig. 3. These ribs 15 terminate in sloping surfaces normally positioned far enough above the upper end 65 of the cylinder 26 to permit outward movement of the locking elements 64 in case the piston 60 and contact member 22 are shifted downwardly relative to the abutment 68, so that the piston will then be prevented from continuing such downward movement prior to full movement of the contact member out of circuit closed position. The upper end 66 of the cylinder 26 is provided with suitable slots 66a for receiving the several ribs 15 of the movable abutment when the latter element is moved downwardly. It will thus be seen that if the piston 6%) is positioned to cause the locking elements 64 to engage the cylinder end 66, subsequent downward movement of the movable abutment 68 will result in engagement of the ribs 15 with the locking elements to force them inwardly to permit entry thereof into the cylinder.

Slidably mounted in engagement with the wall 45 of the body 44 is a sleeve member 18, on the lower end of which is formed a flange 18 engageable with the outer surface of cylinder 26. The sleeve member 18 has formed therein a bore in which there is slidably mounted an enlarged portion of the movable abutment 68, it being understood that the sleeve member and movable abutment are thus adapted for independent motion along the axis of the cylinder. For preventing rotary movement of the movable abutment 68 with respect to the sleeve member 18, there is provided one or more vertically disposed pins 82 each of which is screwed into a suitable threaded hole in the enlarged portion 80 and fitted in sliding engagement in an aligned bore formed in the flange 19 of the sleeve member. An annular member 83 is mounted in screwthreaded connection with the upper end of the sleeve member 18 for sliding engagement with the outer surface of the movable abutment 68, the upper surface of this annular member being adapted to be moved into abutting relation with a plurality of shoulder portions 85 formed within the body 44. An inlet opening 33a is formed in the body 44 adjacent the shoulder portions 85 for admitting fluid under pressure from the pipe 33 to an annular space 33h to which the upper surface of the annular member 83 is always exposed. The movable abutment 68 is provided with a port 81 which is adapted to be moved into registration with this annular space 331) upon downward movement of the abutment, as hereina-iter explained.

A plurality of annular bumper elements 98 formed of resilient material, such as rubber, are interposed between the lower surface of the annular member 83 and the upper surface of the enlarged portion 86 of the movable abutment 68. Suitable spacing washers 9| may be provided for separating the resilient elements 90, the lowermost washer 9| being adapted to rest on the enlarged portion 88 when the parts arc positioned as shown in Fig. 3. The upper surface of the portion 86 is chamfered to provide an annular space 93 adjacent the washer 8|, which annular @visait-.286

'7 ,space is adapted to register with an elongated por-t 194 formed in the wall `of the sleeve `iriember ,'18 and communicating with the port 53 of the body 44.

A coil spring 95 is interposed between the casing section 4| and the ange '|9 for urging the sleeve member 'I8 upwardly to the `position illustrated, wherein the annular member 83 is held Ain engagement with the shoulder portions y85. A similar coil spring 96 is interposed between the lange 79 and the enlarged portion 80 of the movable abutment 68 and serves to hold the latter in its uppermost `position wherein the enlarged portion 85 engages the lowermost washer 9| while ,the rib portions '|5 are disposed above the upper end .6,5 of the cylinder. For preventing rotation of the sleeve member 18 with respect to the casing structure, there is provided at least one vertically disposed pin 91, the upper end of which may be secured in screw-threaded connection with the flange I9 and the lower end of which is 3mounted in sliding engagement within a suitable bore formed in the casing section 4|. The kpin 9'! is preferably of such length as to extend outwardly of the casing section 4| so that when it is desired Vto disengage the locking elements 64 carried by the piston in order Yto permit manual movement of the contact mem-ber 22, as in adjusting the circuit breaker mechanism, the outer end of the pin Sl may be grasped and pulled downwardly for operating the movable abutment S8 without the use of fluid under pressure.

As ,already explained, the circuit breaker is i1- lustrated as disposed in circuit closed position, `the movable contact member 22 being held in engagement with the usual stationary contact element. In Fig. 3, the piston .60 is shown in its uppermost position with the locking elements A511 held in released position by the ribs 15 of movable abutment `58. If, under the .influence ,of gravity or other forces, the movable contact-member 22 and piston Se should tend to settle downwardly, the locking elements 84 will -be moved below the ribs 'i5 and will thus be expanded by the springs |55 into operating alignment with the upper Vend 56 of the cylinder, thus preventing ,downward movement of the piston far enough to cause disengagement of the movable contact member v2 2 from the stationary contact element.

Upon initiation of an opening operation of the circuit breaker, fluid under pressure is supplied in the usual manner to the conduit `|ll shown in Fig. 2, and flows therefrom through the conduit 36 tothe blast passage 39 in blast `tube 20. At the same time, fluid under pressure is supplied from I the conduit 38 through pipe 3B, the communications within the valve device 28, and pipe 3 3 to the port 33a shown :in Fig. 3. rhe pressure of fluid in the passage 39 acts downwardly on the upper portion ci the movable abutment v|58 at substantially the same .time as the pressure of ilu-id supplied to the port 33a becomes effective on the upper surface of the annular member 83, the pressure on the latter member being also exerte on the Inova-ble abutment through -the medium of the compacted resilient elements Se and washers The movable abutment E8 is thereby shifted downwardly yto insure positioning of the locking elements 64 to permit entry thereof into the cyl.- inder Z, as hereinbefore explained. This downward movement ,of the movable abutment also brings the spring elements 2 into operating eneasement with the piston BB, and as a result the piston and movable contact member 2,2 are quicklyshifted downwardly under an initial accelerating force vdeterminedby lthe entire pressure arca .of the movable ,abutment .6.8. Downward move.- ment of the movable abutment 5,8 .also brings -the port 8l therein into registration with rthe annular space 33D, whereupon iluid under pressure is supplied from the pipe 33 through this yport and through the space dened between the cylinder 26 and the movable abutment lto ,-thepiston chamber 62 above the piston 60.

The pressure of fluid thus admitted to the chamber 62 then forces the l`piston 60 and the movable contact member 22 downwardly 4within ,the cylinder 26, independently of the movable vabutment B8 which ,meanwhile comes to a stop. It should be understood that the movable ,contact member -22 is sldably engageable with the stationary contact member .5 through vat least the initial part of its .traverse lcorresponding to movement of the piston 60 from the .normal position, as illustrated in Fig. 3, to a, position .within 1the cyl- Vinder 2G following release of the lockingelements 64 bydownward movement of the movable abut.- inent 68, as hereinbefore explained. Upon continued movement o f the piston .S0 and .Contact member 22 under the pressure of fluid in ,chamber S2, however, the contact member Vis pulled downwardly and away from the stationary contact element to interrupt the circuit controlled by the pole unit shown in the drawings. Meanwhile, the blast of fluid under pressure already flowing through the blast conduit 1210 is eiective to `extinguish the arc drawn between the separating contact elements. The supply of fluid to the circuit breaker is finally terminated by automatic operation of the usual opening valve mechanism associated with the equipment.

The coil spring is adapted to yield during downward displacement of the sleeve member 18 -when iluid underpressure is admitted to the space 33h above the annular member 83, while the spring S6 is adapted to yield to permit downward movement of the movable abutment 58 relative to the sleeve member.

If the usual control system associated with the pole unit, as shown in Fig. 2, becomes operative to effect a closing operation immediately after completion of a circuit interrupting operation, the supply of iluid under pressure to the conduit 3,8 having been cut off, fluid under pressure is then supplied to the pipe 30. Upon supply of ilu-id under pressure to the pipe 30, the ycontrol valve device 28 is operated in the usual manner to .connect the pipe 33, leading from the upper end of the cylinder, to the atmosphere, while establishing communication from the pipe 30 tothe pipe 3|. The pipe 3| communicates with the portion of the cylinder 26 at the lower side .of .the piston, so that uid under pressure is thus supplied ,to the chamber 6| for moving ,the piston 60 and movable contact element upwardly to the circuit closed position. At the same time, fluid under pressure flows from the ypipe 3| past the ball check valve 55 and through the chamber 52 land ports 53 and 94 to ,the annular chamber 93. The pressure of fluid in the annularcharnber 93 is exerted against the portion 8|) Iof the movable abutment B8 to force that member away from the annular washer 9|, inlopposition to the pressure of spring 95. Since the pressure within the blast conduit passage 39 has meanwhile been reduced to substantially that of the atmosphere, the .associated movable abutment 68 and sleeve member 18 are meanwhile .urged .to their normal positions by the forceof gthespring.

Upon ,engagement .of the upwardly moving piston 60 with the assemblage of spring elements 12 mounted in the upper portion of the movable abutment 68, the latter element is forced upwardly against the opposing pressure of the fluid bottled up within the annular chamber 93. The fluid within the chamber 93 is thus further compressed to a degree determined by the adjustment of the spring 58 acting against the relief check valve 51, which is adapted to open to permit escape of fluid by way of the passage 5l. It will thus be seen that the piston B is initially checked upon engagement with the resilient spring elements 'l2 and is thereafter rapidly brought to a stop during compression of the fluid within the space 93, so that the kinetic energy of the piston and of the movable contact member 22 is rapidly dissipated before any severe shock can be transmitted by Way of the cylinder structure to the porcelain structural members of the circuit breaker. Any final force with which the portion 80 of the movable abutment 68 may be brought against the washer 9| is absorbed by the resilient annular members 90. By reason of the fact that the fluid under pressure entrapped within the annular space 93 can be discharged by way of the ball check valve l during a closing operation of the circuit breaker as just described, undesirable rebound of the moving elements is minimized. It will be apparent that at the conclusion of this operation the various elements of the apparatus are once more positioned as shown in Fig. 3 and the equipment is again conditioned for a normal circuit opening operation.

From the foregoing, it will be seen that a liuid pressure operating mechanism constructed in accordance with our invention may be readily installed in the limited space available in a circuit breaker equipment, and that the pneumatic bumper features of the invention may be designed for use not only at the upper end of the cylinder as shown in the drawings, but also at the lower end if it is deemed advisable tc provide the same means for absorbing shock at the end of a circuit opening stroke of the operating piston.

According to our invention, an efficient means for locking the movable contact element of the circuit breaker in its closed position is provided without the use of a bulky or complicated external latching mechanism, and the movable abutment subject to a pressure of fluid supplied in initiating an opening operation insures not only quick release of the locking means but also rapid acceleration of the movable contact member out of its closed position. By designing this movable abutment so that it may also serve to cushion the return stroke of the piston during a circuit closing operation, we have minimized the number of 0perating parts required and have provided a relatively compact and inexpensive construction.

Having now described our invention, what we claim as new and desire to secure by Letters Patent, is:

1. In a fluid pressure operated circuit breaker, a movable contact member, fluid pressure operated means for moving said contact member into and out of a circuit closed position, means for supplying fluid under pressure to said fluid pressure operated means, holding means for maintaining said contact member in circuit closed position, and auxiliary fluid pressure responsive means operative upon supply of fluid to said fluid pressure operated means, when said contact member is in circuit closed position, to release said holding means and to apply an initial accelerating force to said fluid pressure operated means.

2. In a fluid pressure operated circuit breaker', a movable contact member, uid pressure operated means for moving said contact member into and out of a circuit closed position, means for supplying fluid under pressure to said fluid pressure roperated means, holding means for maintaining said contact member in circuit closed position, fluid pressure responsive means operative by fluid supplied to said fluid pressure operted means in effecting the circuit opening operation to release said holding means, and means for subjecting said fluid pressure responsive means to back pressure in effecting a circuit closing operation for cushioning final closing movement of said contact member.

3. In a circuit interrupter, a contact member movable into and out of a circuit closed position, fluid pressure supply means, operating means actuated by fluid supplied therefrom for'operating said contact member, mechanical means for holding said contact member in said circuit closed position, and fluid pressure responsive means movable relatively to said operating means and operative by fluid pressure applied thereto from said supply means for releasing said holding means and accelerating said contact member out of said circuit closed position.

4. In a gas blast circuit breaker, movable contact means operative into and out of a circuit closed position, a blast conduit for directing a blast of fluid under pressure to said contact means, fluid pressure responsive actuating means for operating said contact means, fluid pressure supply means through which fluid under pressure is supplied to said blast conduit and to said operating means, and means subject to the pressure of fluid in said blast conduit for accelerating initial movement of said operating means.

5. In a gas blast circuit breaker, movable contact means operative into and out of a circuit closed position, a blast conduit for directing a blast of fluid under pressure to said contact means, fluid pressure responsive actuating means for operating said contact means, fluid pressure supply means by which fluid under pressure is supplied to said blast conduit and to said operating means, means subject to the pressure of fluid in said blast conduit for accelerating initial movement of said contact means out of the circuit closed position and means subject to the pressure of fluid supplied to said operating means for cushioning movement of said contact means into circuit closing position.

6. In a gas blast circuit breaker, movable contact means operative into and out of a circuit closed position, a blast conduit for directing a blast of fiuid under pressure to said contact means, fluid pressure responsive actuating means for operating said contact means, fluid pressure supply means through which fluid under pressure is supplied to said blast conduit and to saidv operating means, and fluid pressure responsive means operative at one time by the pressure of fluid in the blast conduit for accelerating movement of said contact means to circuit closed position, and operative at another time, upon supply of fluid under pressure to said operating means for moving said contact means to circuit closed position, for cushioning nal movement of said operating means.

7. In a gas blast circuit breaker, movable contact means operative into and out 0f a circuit closed position, a cylinder structure, a piston mounted in said cylinder structure and subject to the pressure of fluid in a chamber for oper- 11 ating said contact means, a1 blast conduit for directing a blast of fluid under pressure `to' said contact means, common supply means for supplying iluid under pressure to saidvblast conduit and to said cylinder structure, and a movable abutment mounted in said cylinder structure and subject to the pressure of fluid in said blast conduit for initially accelerating said piston and then establishing a communication for the supply of fluid under pressure to said chamber.

8. In a iluid pressure operated circuit breaker having a movable contact member, the combination of a cylinder structure, a piston operatively mounted therein and connected to said contact member, means for supplying iluid under pressure into said cylinder structure for operating said piston, a movable abutment slidably mounted in said cylinder structure in cooperative alignment with said piston, said abutmentl having a ilange, and means for yieldingly checking motion of said piston at the end ci a stroke, including a plurality of annular dished spring elements interposed between said piston and said movable abutment and resilient means interposed between said flange and' said cylinder structure.

9. In a iluid pressure operated circuit breaker having a movable contact; member, the combination. of a cylinder, a piston slidably mounted in said cylinder for moving said contact member into and cut of a circuit closing position, a blast conduit adapted to be supplied with iluid under pressure for extinguishment of the arc drawn by said contact member duringa circuit opening operation, means for supplying fluid under pressure to said cylinder for operating said piston, locking means carried by said piston for maintaining said Contact member in its circuit closedv position in the absence of any supply of fluid under pressure to said cylinder for opening the circuitJ breaker, and means subject tor the pressure of fluid in said blast conduit for releasing said locking means.

l0. In a iluid pressure operated circuit breaker having a movable contact member, the combination of a cylinder, a piston slidably mounted in said cylinder foi1 moving said contact member into and out of a circuit closing position, means for supplying and releasing fluid under pressure to and from said cylinder for controlling operation of said piston, a movable locking element carried by said pistonand arranged t automatically engagev one end of said cylindei` to check undesired movement of said contact member and piston from the circuit closed position in the absence-of any supply of fluid under pressure to said cylinder, and fluid pressure responsive means operative to move said locking element out of engagement with said end of said cylinder upon supply of iluid under pressure to said cylinder for effecting a circuit opening operation.

11. In a fluid pressure operated circuit breaker having a movable contact member, the combination of a cylinder, a piston slidably mounted in said cylinder for moving said contact member into and out of a circuit closing Zone, means for supplying fluid under pressure to said cylinder at one side of said piston for operating the same to move said contact member out of said circuit closing zone, locking means operative to limit movement of said piston and Contact member upon predetermined displacement thereof Within said circuit closing zone, anda movable abutment mounted iny said cylinder for movement relative to said piston, said abutment being operative to release said locking means when fluid under pressure is supplied to said' cylinder for eiecting a 12 normal circuit openingl operation of the' circuit breaker.

l2. In a fluid pressureV operated circuit breaker, the combination of a movable contact member, a casing structure including a stationary cylinder, a piston mounted in said cylinder for operating said contact member, means for supplying vfluid under pressure to said cylinderv for operating said piston, locking means carried by said piston and normally cooperative with said stationary cylinder for preventing undesired displacement of said piston and Contact member, and a movable abutment slidably mounted in said casing structure in operative alignment with said piston, said abutment being operative upon an increase in fluid pressure to disengage said locking means and to accelerate said Contact member and piston,

13. In a iluid pressure operated circuit breaker, the combination of a movable contact member, a casing structure including a stationary cylinder, a piston mounted in said cylinder for operating said contact member, means for supplying iluid under pressure to said cylinder for operating said piston, locking means carried by said piston and normally cooperative with said stationary cylinder for preventing undesired displacement of said piston and Contact member, and a movable abutment slidably mounted in said casing structure in operative alignment with said piston, said movable abutment being operative by a iluid under pressure for disengaging said locking means and for substantially simultaneously es-` tablishing communication for supply of fluid under pressure to a working face of said piston.

14. In a fluid pressure operated circuit breaker, the combinationlof a movable contact member, a casing structure including a stationary cylinder, a piston mounted in said cylinder for operating said contact member, means for supplying iluid under pressure to said cylinder for operating said piston, locking means carried by said piston and normally cooperative With said stationary cylin der for preventing undesired displacement of said piston and Contact member, and a movable abutment slidably mounted in said casing structure inoperative alignment with said piston, said movable abutment being responsive to the pressure of fluid supplied for operating the circuit breaker for releasing said locking means and admitting fluid under pressure to a Working face of said piston.l

l5. In a iluid pressure operated circuit breaker, in combination, movable contact means movable into and out of a circuit closing position, a casing structure including an inner cylinder and an outer cylinder, a piston mounted in said inner cylinder and connected to said contact means, a movable abutment cooperative with said piston and having an annular portion interposed between said inner and outer cylinders, means for supplying fluid under pressure to said inner cylinder for operating said piston to move said contact means to circuit closed position, and means for simultaneously subjecting the portion of said movable abutment interposed between said cylinders to an opposing pressure for cushioning'ilnalmovernent ofsaid piston and contact means.

16. In a iluid pressure operated circuit breaker,

a movable contact member operative into' and out of a circuit closed position, a blast conduit for directing a blast of lluid under .pressure to said contact means, a casing structure mounted adjacent said blast conduit and having an inner cylinder andan outer cylinder, a piston mounted.-

in said inner cylinder and connected to said movable contact member, a movable abutment having an annular flange portion slidably mounted in said outer cylinder, means for supplying fluid under pressure to said blast conduit and to said outer cylinder in effecting an opening operation of the circuit breaker, said movable abutment being subject to the pressure of fluid in said blast conduit and operative to control supply of iiuid under pressure from said outer cylinder to said inner cylinder at a working face of said piston, and locking means carried by said piston for maintaining said movable contact member in circuit closed position, said locking means being releasable by operation of said movable abutment in response to supply o-f fluid under pressure in effecting an opening operation of said circuit breaker.

1'7. In a fluid pressure operated circuit breaker, a movable contact member operative into and out of a circuit closed position, a blast conduit for directing a blast of fluid under pressure to said contact means, a casing structure mounted adjacent said blast conduit and having an inner cylinder and an outer cylinder, a piston mounted in said inner cylinder and connected to said movable contact member, a movable abutment cooperative with said piston and having an annular flange portion slidably mounted in said outer cylinder, means for supplying fluid under pressure to said blast conduit and to said outer cylinder in effecting an opening operation of the circuit breaker, said movable abutment being subject to the pressure of fluid in said blast conduit and said outer cylinder and operative to control supply of fluid under pressure from said outer cylinder to said inner cylinder at a working face of said piston, locking means carried by said piston for maintaining said movable contact member in circuit closed position, said locking means being releasable by operation of said movable abutment in response to supply of fluid under pressure in effecting an opening operation of said circuit breaker, means for supplying fluid under pressure to said inner cylinder for effecting operation of said piston to move said contact member toward circuit closed position, and means for entrapping uid under pressure in said outer cylinder adjacent said flange portion of the movable abutment for cushioning nal movement of said piston at the end f a circuit closing operation.

18. In a fluid pressure operated circuit breaker having supporting insulator members, a casing section mounted thereon, arc extinguishing means including a blast conduit of insulating material mounted on said casing section, and relatively movable contact means mounted within said arc extinguishing means, the combination therewith of compact fluid pressure responsive operating means comprising a cylinder mounted in said casing section and extending beyond said casing section at either end, a piston operatively mounted in said cylinder for actuating said contact means, said piston being movable through a stroke exceeding the distance between said supporting insulator member and said blast conduit, and shock absorbing means arranged annularly about said cylinder for cushioning operation of said piston.

19. In a uid pressure operated circuit breaker, the combination of a movable contact member, a casing structure including a stationary cylinder, a piston mounted in said cylinder for operating said contact member, means for supplying fluid under pressure to said cylinder for operating said piston, locking means carried by said piston and normally cooperative with said stationary cylinder for preventing undesired displacement of said piston and contact member and means operatively disposed annularly about said cylinder and responsive to fluid under pressure supplied thereto for operating said locking means.

20. In a fluid pressure operated circuit breaker, the combination of a movable contact member, a casing structure including a stationary cylinder, a piston mounted in said cylinder for operating said contact member, means for supplying fluid under pressure to said cylinder for operating said piston and accelerating means mounted annularly about said cylinder intermediate the ends thereof, said accelerating means being responsive to pressure of fluid supplied to said cylinder for initially augmenting the force applied to said piston for accelerating same.

21. In a fluid pressure operated circuit breaker, the combination 0f a movable contact member, a casing structure including a stationary cylinder, a piston mounted in said cylinder for operating said contact member, means for supplying iiuid under pressure to said cylinder for operating said piston and cushioning means disposed annularly about said cylinder intermediate the ends thereof for absorbing shock at the end of a stroke of said piston.

22. In a fluid pressure operated circuit breaker, a movable contact member, fluid pressure -operated means for moving said contact member to open and closed circuit positions, means for supplying uid under pressure to said uid pressure operated means, locking means for maintaining said contact member in one of said positions, additional fluid pressure responsive means operative upon supply of fluid to said uid pressure operated means when said contact member is in said one position to release said locking means, and means whereby said additional fluid pressure responsive means applies an initial accelerating force to said uid pressure operated means.

23. In a circuit breaker having a movable contact member, a cylinder, a piston in said cylinder for actuating said contact member, a movable abutment disposed in the path of movement of said piston, resilient means disposed between said abutment and said piston, means for supplying fluid under pressure to said cylinder to cause movement of said piston in a given direction, said abutment having two surfaces adapted to be acted upon by iiuid under pressure, means for subjecting at one time one of said surfaces of said abutment to fluid under pressure to cause said abutment to cushion at least the final movement of said piston in said given direction, and means for subjecting at another time the other of said surfaces of said abutment to fluid under pressure to cause said abutment to apply a force to said piston through said resilient means to initially -accelerate said piston in the opposite direction.

OSWALD voN MEHREN. BENJAMIN P. BAKER.

REFERENCES CITED UNITED STATES PATENTS Name Date Johnson Oct. 1'7, 1944 Number 

